The invention relates to a method and device for automatically aligning a work piece and positioning the aligned work piece at the stitch forming location of a sewing machine.
Prior art reference U.S. Pat. No. 4,467,734, discloses an edge guide and material advancing device for seaming a tubular work piece and forming a fold at its edge. The tubular work piece is manually located on the sewing machine work surface, such that it is in the proper location to commence the sewing operation. After positioning the work piece, but before commencing the sewing cycle, a work positioning device is activated which moves a portion of the material and creates a surplus of material near the work piece edge. The work piece edge is not moved from its original location. This surplus of material acts as a material buffer or storage zone which facilitates the aligning of the work piece edge by making possible a shifting of the work piece edge without having to shift the entire work piece in a direction transverse to the sewing direction. In accordance with the invention of this prior art patent the plies of material to be stitched are properly aligned and manually located at the stitch forming location by the sewing machine operator. Thus this prior art reference does not eliminate the tedious and time consuming task that is eliminated by the subject invention.
When seaming two plies of cloth together, a sewing machine operator manually aligns the leading and margin edges of the plies of cloth, in the relative positions that they are to have when stitched together, and then locates the aligned plies under the presser foot of the sewing machine. This is a very tedious and time consuming portion of a sewing operation and the operator must be highly skilled to perform this operation efficiently and properly.
For the foregoing reasons, there is a need for a device and method that will automatically align both the leading and the margin edges of the work piece and then position the work piece in the correct relationship at the stitch forming location prior to commencement of the sewing operation.